Many optical devices rely on the use of and/or interface with forms of fluid media for transmitting radiation. In various applications, certain types of fluid material may provide a necessary medium through which targets are analyzed or treated and for providing safe malleable structural support to a device component. For example, certain types of bio-sensitive material may be damaged or degraded when exposed to air or other environmental factors. When examining or treating bio-sensitive material with light radiation, a relatively safe intervening fluid media is generally preferred. For example, a liquid media such as water might be used to interface with the internal tissue of a patient (e.g., for displacing tissue material, cleaning, and cooling) where that tissue would otherwise be damaged by a direct interface with air
The displacement of blood and tissue debris by the introduction of a temporary fluid media is useful, for example, in inspecting narrow passages including blood vessels. Fluid media may be used to provide temporary physical support for holding catheter probes in place during treatment and/or analysis. For example, U.S. Pat. No. 5,964,751, the entire contents of which are incorporated herein by reference, characterizes a catheter having an expandable balloon at its distal end through which the interior surfaces of vessels are treated with radiation. Fluid media relied upon for inflating balloons and providing optical media, in particular, have included gases such as air, CO2, and helium or liquids including water and ordinary saline solution of about 0.85% salinity (or a percentage of grams of dissolved NaCl per milliliter of water). Other systems include a process by which blood and other artifacts are directly flushed out of an area targeted for radiation transmission or collection. Flushing a biologically sensitive area with a fluid media can also be useful for preventing overheating, such as during a tissue ablation procedure with the use of a high-energy laser.
The adopted media through which to examine or treat tissue or other delicate material, however, has suffered from many drawbacks, including safety risks, restrictions in fluid dynamics, and/or significant interference with radiation traveling through the media. For example, the sudden release of air or hydrogen into a patient's bloodstream from a broken balloon or similar device could result in injury and/or death. Furthermore, providing sufficient pressure to properly inflate a catheter balloon (e.g. 8-12 atmospheres in an angioplasty type balloon) with a gas such as air or helium through the narrow passages of a catheter could be difficult and/or prohibitively expensive. Water and ordinary physiological saline solution detrimentally absorb and scatter a significant level and range of optical radiation, including many wavelengths in and outside the visible spectrum, and can thus affect the power profile, footprint, cost, and/or complexity of many systems requiring the use of fluid media through which to transmit or collect radiation. Thus, there is a need for providing transmission media that is both safe for introduction into a patient, is practical, and is of improved transmissive efficiency.